Polysiloxane coatings for electronic, optoelectronic, and display devices are disclosed, for example, in U.S. Pat. No. 8,901,268, entitled, COMPOSITIONS, LAYERS AND FILMS FOR OPTOELECTRONIC DEVICES, METHODS OF PRODUCTION AND USES THEREOF, the disclosure of which are hereby incorporated by reference in their entirety.
In a typical polysiloxane coating, the coating is formed from a hydrolysis and condensation reaction of silicon-based compounds, such as siloxane monomers or oligomers, often with the use of a condensation catalyst. Such coating formulations may be associated with certain limitations, including one or more of limited shelf life, lower pH, the presence of water in the formulation, and limited film thickness.
In some typical coatings, film thickness is limited due to restrictions on the solid content of the formulation. At too high of a solid content, the polymerization reaction has a tendency to react until the formulation becomes gelled, rendering it unsuitable for forming an electronic or optoelectronic coating. In some typical devices, the polysiloxane coating is applied to a substrate or coating that is sensitive to moisture. Application of a formulation containing water to the substrate or coating may damage the moisture sensitive material, such as siloxane materials that contain Si—H entities, which are sensitive to moisture. In some typical devices, the polysiloxane coating is applied to a substrate or coating that is sensitive to pH. Application of a formulation to the substrate or coating may damage the pH sensitive material, such as metallic patterns of interconnects that may be sensitive to acidic or basic media.
In addition, touch-enabled high pixel density (pixel per inch or ppi) displays with increasing battery life and higher viewing pleasure require increasing individual pixel operation by minimizing power consumption at the thin film transistor (TFT) level. For touch-enabled advanced displays with higher resolution individual pixels are connected to multiple thin film transistors (TFTs) to achieve maximum resolution and maximum pleasure of viewing for consumers. Building thermally-stable oxide TFTs on a smooth substrate by applying a thermally stable planarization layer on the solid substrate, preferably glass, decreases leakage during TFT operation and lowers power consumption during switching on and off of the device. Oxide TFTs, such as indium gallium zinc oxide (IGZO) have low off current, providing long battery life for a display device compared to amorphous and low temperature polysilicon TFTs. Copper, aluminum, or molybdenum interconnects require a thermally stable (350° C.-400° C., preferably 380° C.) planarizing dielectric material for oxide TFT with low out gassing. Additionally, interconnects of copper, aluminum, or molybdenum require a relatively thicker barrier material, such as silicon nitride, to prevent diffusion, which generally adds to the fabrication costs. However, typical planarization materials do not meet the requirements to be an effective diffusion barrier or a supplementary diffusion barrier.
Improvements in the foregoing are desired.